This invention relates to an electrodynamic actuator, which in a preferred embodiment, can be used in a wire matrix printer.
A wire matrix printer forms visual characters by impacting groups of elongated printing elements against a platen with a record medium and generally an inked ribbon positioned between the platen and the printing elements. In some of the printers, an entire character is printed at one time, requiring thirty-five printing elements and actuators to print a 5.times.7 matrix character, for example. In other printers, 7 or 9 printing elements, for example, may be arranged in a line adjacent to the platen, and a character is formed by energizing selected ones of the printing elements as the line of printing elements is moved in a direction which is perpendicular to the line of printing elements. The following list of U.S. Pat. Nos. is representative of various wire matrix printers: 3,333,667, 3,833,105, 3,217,640, 3,842,955, and 3,795,298, 3,889,793.
Each of the above named patents discloses a wire matrix printer which utilizes long wire printing elements which need to be supported, and each requires a separate magnet for each of its associated actuators.
In contrast with the above, the actuator of the present invention, when utilized as a printer, utilizes a single magnetic means for a plurality of printing elements. In the present invention, no expensive print wire guides to support the printing elements are necessary and no special spring elements are needed to retain each of the printing elements in an inoperative position. The printing elements are very short and each is mounted on the periphery of a self supporting disc and impacts against a platen as a result of a tangential force applied to the associated disc. The actuator of the present invention is also economical to manufacture, due to its very simple construction.